Nix Configs
Setup on macOS
First you need the nix package manager installed:
curl https://nixos.org/nix/install | sh
and initialized in your .zshrc:
if [ -e $HOME/.nix-profile/etc/profile.d/nix.sh ]; then . $HOME/.nix-profile/etc/profile.d/nix.sh; fi # added by Nix installer
Next, we need a virtual linux environment in which to build our packages, as most builds require x86_64 gnu_linux. One option is linuxkit-nix (remember to check their readme on github for a later version):
nix-env -i /nix/store/jgq3savsyyrpsxvjlrz41nx09z7r0lch-linuxkit-builder
Currently, linuxkit-nix installs the config to ssh into the vm in ~root. Later versions will be smarter, but for now copy the contents of this file into your local ssh config:
sudo nvim /var/root/.ssh/nix-linuxkit-ssh-config
Then run the following:
nix-linuxkit-configure
The vm does not always start up successfully, particularly after a reboot. You can quickly check if it is running by trying to ssh into it:
ssh root@nix-linuxkit
For now, if you experience trouble, the quicket solution I've found is to clear it out and reconfigure it (hopefully the underlying error will not be present in later versions):
rm -rf ~/.cache/nix-linuxkit-builder
nix-linuxkit-configure
Deploying to Digital Ocean
The nixops build process will look for NIX_REMOTE_SYSTEMS when deciding where to
try and perform part of the build. linuxkit-nix has already initialized a file that
points to its vm, so it's easiest to point NIX_REMOTE_SYSTEMS to that:
export NIX_REMOTE_SYSTEMS="/etc/nix/machines"
You'll also need your auth token available in your env, or digital ocean will reasonable not let you interact with your account:
export DIGITAL_OCEAN_AUTH_TOKEN='your-auth-token'
For easy ssh, store your ssh key in a file in the do directory, and name it
adc-public-key.nix. The file should look like this:
[ "your-public-key" ]
One last gotcha: you'll need to use the source code/unstable branch of nixops if you want your DO instance to be initialized with the nixos 19.03 channel as default. This is likely to change in an upcoming release.
Once the above is done:
nix-env -i nixops
cd do
nixops create ./adc-server.nix -d adc-server
./setup
Other gotchas
I have experienced issues initializing an ssh connection with digital ocean immediately after the droplet is created in the setup process. This usually happens when I've been doing a lot of deploying and destroying. I haven't yet found the underlying cause of the issue, but for now, rebooting the system clears it up.